Oven



Dec. 13, 1949 H J @OTT 2,491,420

Filed Jan. 30, 1947 4 Sheets-Sheet l Mam Nyo? im# Dec. 13, 1949' H. J. scoTT 2,491,420

ovEN

Filed Jan. :50, 1947 1 4 sheets-sheet 2 H. J. SCOTT Dec. 13, 1949 OVEN Filed Jan. 30, 1947'4 4 'Sheets-Sheet 3 Dec. 13, 19,49 H, SCQTT 2,491,420

ovEN v Filed Jan. 30, 1947 4 Sheets-Sheet 4 Y l.- N V u "H 1 l I -1&1 l.. +l

Patented Dec. 13, 1949 OVEN Henry Joseph Scott, Surbiton, England, assignor to J. Lyons and Company Limited, London, England, a British company Application `lanuary 30, 1947, Serial No. 725,226 In Great Britain September 4, 1946 4 Claims.

This invention relates to ovens designed for heating materialparticularly food-contained in containers.

The invention is specially concerned with the provision of means whereby cooked food-which may have been frozen after it has been cooked contained in containers can be brought to a desired edible temperature.

The problem arises in acute form in the case of the galleys of aeroplanes.

A method of providing hot meals under such circumstances is to provide the meals in courses transportable to the aeroplane as solid frozen blocks and bring them to the required tempera ture on the aeroplane as required.

This can be effected in electrically heated ovens but the amount of current available under such circumstances is limited and must then.- fore be used to the best advantage and, moreover, it is necessary that a number of meals or courses, for example twenty, must be served simultaneously and must all be brought to their desired temperature at the same time. Seeing that each of the meals or courses must be heated in a container an oven to meet the requirements appropriately consists of a number of shelves or runners arranged one above the other on to which the containers can be slidden and the primary problem that arises is to ensure that the heat distribution is equal throughout the oven. It is difficult to attain this even heat distribution, paru ticularly with ovens of large size, and unless this condition is effected the result is that while the meals or courses located in one part of the oven attain the desired temperature, in a given time, others in other parts of the oven, do not.

The primary object of the present invention is to remedy this defect and provide an oven of a size adequate for practical use in such places as the galleys of aircraft, restaurant cars, hospitals and the like wherein substantially the same heat ing conditions obtain throughout the whole of the oven so that the meals or courses are heated equally whether they are located at the top, bottom or middle sections of the oven.

According to the invention this desireatum is accomplished by the circulation of the air contained within the oven in contact with heating elements in combination with specially arranged deilectors and diffusion means designed to ensure this even heat distribution.

To attain this desired result we have found two conditions need to be established. In the first place it is necessary that all, or substantially all, the air circulated must be evenly heated and, in the second place, this evenly heated air must be caused to pass evenly in contact with the containers.

The invention consists broadly of an oven comprising heat insulated outer walls, a heating chamber located within and separated from said outer walls, openings in the rear wall of the heating chamber, a door closing against said insulating walls at the front, side chambers between the heating chamber and the insulating walls open to the front of the heating chamber, air heating elements in said side chambers, a rear fan chamber between the rear of the heating chamber and the rear outer insulating wall, an air circulating fan located in said fan chamber and operating to circulate air continuously in contact with the heater elements from its delivery side, across the heating chamber from iront to back, through openings in the rear wall of the heating chamber back to the suction side of the fan and means for ycontinuously driving the fan.

An oven according to the invention is illustrated in the accompanying drawings, wherein:

Figure l is a Vertical side section;

Figure 2 is a plan;

Figure 3 is an elevational view of the back plate assembly of the heating chamber viewed from the front;

Figure 4 is a similar view of said back plate assembly viewed from the back;

Figure 5 is a side elevational view of Figure 4;

and

Figure 6 is a diagram of the preferred electrical connections.

Referring to these drawings the numeral l designates the outer heat insulating Walls which constitute a heating chamber containing `box which is closed by a door 2. This door 2 in its closed position seals against sealing strips 3 so as to hermetically seal the oven. It is hinged by means of the linkage 2a so that on opening by means of the handle l it will come to a horizontal position and will constitute a platform or table upon which the containers can be temporarily rested when they are removed successively from the oven. The heating chamber is located within this insulating box structure and its walls are separated from the Walls of the box structure so as to provide side chambers 5 for containing heating elements and a rear chamber 6 for housing the air circulating fan 1. This air circulating fan 1 is mounted on a spindle having bearings in the rear insulating Wall and the outer end of this spindle is provided with a pulley 8 which is driven by means of a -belt 9 from an electric motor I0 3 mounted on the top of the box-like insulating structure.

Within the heating chamber, which is built up of side walls II and a rear wall I2, runners or shelves I3 are arranged to support removable containers which can be slidden into and out of position from the front of the oven and at the rear ends of these runners, structures having bayonet slots I4 are provided to receive removable hinged cover plates to constitute closing lids for the containers when the latter are in situ in the oven as more particularly described in co-pending application British No. 26,593/46. In the side chambers 5 the heater elements l5 are located and these elements are electrically connected to a source oi current by terminal connections I6 which pass through and are supported in the rear wall of the outer insulating containing box. These heater chambers 5 are open to a space at the front of the oven and the arrangement is such that the air contained in the oven is circulated from the delivery side of the fan 1 into contact with the heater elements to this front space whence it passes across the voven from front to back over and beneath the containers Il and around their sides, and then through openings back to 'the suction side of the fan '1.

As before indicated it is of capital importance that there shall be an even distribution of the heated air in respect of each of the containers so that they all enjoy the same heating conditions and come to the desired temperature at the same time.

In order that this may be accomplished the back plate of the heating chamber needs to be f specially constructed. Reference to Figures 3, 4 and 5 shows this special construction.

In order to ensure that the air induced by the fan action shall be evenly drawn 'across the heating chamber and not take apath of least resistance back to the suction side of the fan, We provide louvred openings I8 of diierent areas arranged at different parts ofthe area of the back plate. As will be seen from lFigure 3 the areas of these openings at the top `and bottom of the oven are greater than inthe middle section and they gradually diminish in area yfrom the top and bottom towards the middle. -It will also be seen that the louvres 18a (see Figure l) are directed downwardly from the top and upwardly from the bottom so that the air passing through the openings I'I is directed towards the suction opening of the fan 1. The precise measurement of the openings may vary within limits without serious detrimental eiect but by way of example we have found that for a nine tier oven having a back plate measuring one foot ve and three sixteenth inches by ten and iive eighths inches satisfactory results will be attained if the extreme top and bottom slots measure nine and ve eighths inches by half an inch, the next pair nine and iive eighths inches by three eighths of an inch, the next pair nine and five eighths inches by ve sixteenth of an inch, the next pair nine and ive eighths inches by a quarter of an inch and at the middle section openings are provided measuring two and a half inches by three sixteenth inch located on each side and above and below the middle container.

Another quite important consideration is the distribution'of the air'from the delivery side of the fan into contact with the heater elements so that the air-itself shall all be evenly heated, To accomplish this we provide delector plates or battles Ib is the fan chamber at the back of the back plate.

A suitable arrangement and conformation of these bailes is shown in Figure 4 from which it will be seen that these plates or baffles radiate at different angles and are arranged symmetrically around the ian so as to cause the air prese sure to build up around the fan and be directed evenly into the side chambers containing the heater elements.

The example of the invention illustrated herein is for an electrically heated oven and Figure 6 gives a circuit diagram of the electrical connections. 'Ihe main terminals for the heater elements and motor are indicated at I9 and are connected to the heater elements I5 and to the motor I0. lThe heater circuit is controlled from a switch 2| and the motor circuit from a switch 22. A limit thermostat 23 and a time switch 24 and warning lights 25 and magnetic relay switches 26 are employe-d in accordance with known practice except that the inclusion of a time switch is a feature of the invention. By the use of a time switch the equipment is rendered completely foolproof. That is to say the particular time period required for bringing the contents of the containers to the desired temperature can be predetermined and the subject of direction to the operator so that all the operator has to do to introduce the containers into the oven and set the time switch to open after the required period and close the controlling switches. The time switch will operate when the material is heated and ready for use.

The warning lights will indicate any failure of the heater elements so that all the operator has to do is to keep an eye on the warning lights to be sure that the oven is operating properly and remove the containers and distribute their contents when the time switch operates and its associated buzzer or bell sounds.

For this reason the invention is particularly advantageous for use in the galleys of aircraft cr the kitchens of restaurant trains. A stewardessor waiter can deal with and dispense food in perfect condition at a given time, no cooking skill being required. It is to be understood that the term air heating elements used in the claims is not to be construed as limited to electrical heating elements as, obviously, gas or even superheated steam heaters could be employed, the gas or steam being supplied to the heaters through a pipe or lpipes passing through a wall or walls of the insulated containing box in place of the electrical terminal connections I6.

I claim:

l. Anoven of rectangular cross section comprising heat insulating outer walls, a heating chamber of rectangular' cross section located within and separated from said outer walls, louvred openings of different area distributed at diierent positions of the rear wall of the heating chamber whereby the heated air is baied and caused to be distributed evenly throughout the heating chamber, a hinged door closing against said insulating walls at the front, side chambers between the heating chamber and the insulating walls open to the iront of the heating chamber, air heating elements in said side chambers, a rear ian chamber 'between the rear of the heating chamber the rear outer insulating wall, an vair circulating fan located in said ian chamber and operating to circulateair continuously in "contact withthe heater elements from its delivery side, across the heating chamber from iront to back through openings in the rear wall of the heating chamber haelt to the suction side oi' the ran and means for continuously driving the fan.

2. An oven of rectangular cross section comprising heat insulating outer walls, a heating chamber of rectangular cross section located within and separated irons said outer walls, openings in the rear wall oi the heating chamber, a hinged door closing against said insulating walls at the front, side chambers between the heating chamber and the insulating walls open to the front of the heating chamber, air heating elements in said side chambers, a rear fan chamber between the rear of the heating chamber' and the rear outer insulating wall, air deiiecting vanos located in the fan chamber, an air circulating fan located in said ian ch bei radiating from the fan center and orinii channels leading to different po' ons or the side chambers containing the heater elements and operating to circulate air continuously in contact with the heater elements from its delivery side, across the heating chamber from iront to basis through openings of graduated area in the rear wall of the heating chamber haelt to the suction side of the fan and means for continuously driving the fan.

3. An oven according to clairn 2, wherein the radiating vanes bridge a gap between the rear outer insulating wall and a plate having an opening leading :troni a suction chamber at the rear of the heating chamber to the circulating fan so that a box-lil e ian chamber is constituted having a number oi side openings leading from the delivery side of the fan to the side chambers containing the heatine elements and a iront opening leading to the suction side of the ian.

4. An oven comprising in combination an outer heat insulating housing composed of two parallel opposite heat insulating vertical outer side walls, two parallel opposite heat insulating horizontal outer side walls secured to the corresponding edges of said opposite heat insulating vertical outer side walls, and a heat insulating vertical outer rear wall secured to the rear edges of said heat insulating outer side walls; a heating chamber located within said heat insulating housing and composed of two parallel opposite vertical inner side walls arranged spaced from said parit allel opposite heat insulating vertical outer side Walls extending between said parallel opposite heat insulating horizontal outer side walls, and a Vertical inner rear Wall extending between the rear edges of said parallel opposite inner side walls and said parallel opposite heat insulating horizontal outer side walls; a door hingedly Secured to the iront edge oi the lower of said parallel opposite heat insulating horizontal outer side walls so as to be adapted to be moved from horizontal open position into vertical closed position abutting against the vertical front edges o said parallel opposite heat insulating vertical outer side walls and the horizontal front edge of the upper or" said parallel opposite heat insulating horizontal outer side walls but leaving communicating passages between itself and the vertical front edges of said parallel opposite vertical inner side walls; side chambers located :between said parallel opposite heat insulating vertical outer side walls and said parallel opposite vertical inner side walls and being open at their iront ends; electrical air heating elements arranged in said side chambers; a rear fan charnoer between said heat insulating vertical outer rear wall and said vertical inner rear wall; an air circulating fan arranged in said rear fan chamber; openings in said vertical inner rear wall of said heating chamber; and means for continuously driving said air circulating fan so as to circulate air continuously from its delivery side into said side chambers into contact with said eiectrical air heating elements, from said side chambers through said communicating passages into the iront end of said heating chamber, through said heating chamber from front to back and through said openings in said vertical inner rear Wall back to the suction side or said air circulating fan.

HENRY JOSEPH SCOTT.

REFERENCES CITED The following references are or record in the le of this patent:

UNITED STATES llurnber Name Date 1,398,542 Forshee Nov. 29, 1921 1,657,205 Ehrgott Jan. 24, 1928 1,986,088 Wild Jan. 1, 1935 2,314,592 McCormick Mar. 23, 1943 

